Heat and glare through your windows in summer

It's July, three in the afternoon. The sun sits directly opposite the window, the monitor is unreadable, and a room that felt fine in the morning is now hard to breathe in. You lower the blinds and sit in half-darkness in the middle of the brightest day of the year. In the evening the lights come on in the house across the street, and you know your living room is just as visible to them as theirs is to you.

All three problems point back to the glass. There isn't one solution for all of them, and each route does something different.

Heat, glare and being seen are not the same thing

Glass lets in light and radiation that you feel as heat. That heat settles into the floor, furniture and walls, and keeps radiating out long after the sun has moved past the corner. That's why rooms with south- and west-facing windows run warmest, and why such a room is so hard to cool down overnight.

Glare is direct light or a reflection off a desk or screen, and it can happen on a cold March day too. Privacy is only loosely tied to the sun: what matters is which side of the glass has more light. Depending on what bothers you most, the right fix is different too.

Blinds, shutters and curtains

External blinds and shutters catch the sun before it reaches the glass, which makes them a strong option against heat. They need to be fitted to the facade or the window reveal, and in an block of flats that usually means the owners' association has to agree. Once they're down, the view goes with them.

Interior blinds, shutters and curtains are easy to fit and handle glare and being overlooked well. But they only catch the heat once it's already in the room. And when you're protecting your eyes or your privacy, you darken the whole room along with it. Both only work while they're closed.

What tint film on the glass does

Tint film is applied directly to the glass and stays there. It cuts down part of the solar radiation, softens brightness and direct glare, and during the day it makes it harder to see into the room from outside. The view out stays, just a shade darker depending on the tint you choose. Nothing needs lowering, and the film keeps working even when you're not home.

It suits places where blinds can't be fitted, or where you'd otherwise leave them down all summer: an office with a wall of windows, a shop front, a conservatory, a glazed staircase, a roof window that makes the room underneath unworkable in summer. It doesn't compete with external shading — the two can be used alongside each other.

What film won't do

Film is constant. It dims light on an overcast day too, and it cuts into winter sun as well. Where winter light is already scarce, a lighter tint is chosen, or only the windows that get the most sun are covered.

Daytime privacy holds as long as there's more light outside than in. In the evening, once you switch the lights on, the room becomes visible again. It doesn't replace a curtain or a blind at night.

What to ask about beforehand

What kind of glass you have. Single glazing, double glazing and safety glass behave differently in the sun, so talk about the glass type before choosing a film. If you don't know it, a photo or the label in the frame helps.

How the window will look from outside and in the evening. Some films just look darker from outside, others are reflective. Ask for a sample and look at it both in daylight and after dark. If you only cover some of the windows, the difference will show from the street, so in an block of flats discuss the look with the owners' association too. For new windows, check with the manufacturer whether film affects their warranty.

Which windows actually need it. Often it's enough to do the south- and west-facing windows, or just the top part of a large glazed area.

How the film comes off later, in case you want a different shade or you move. It can be removed from glass over time, but ask how it's done and whether it leaves anything behind.

Send us a photo of the window

We apply tint film to car windows and to building windows alike, fitted by Lukáš Vyskočil and Sebastian Vyskočil. What tint film for building windows involves is on the Window Film for Buildings page.

A photo of the window and a few words about what bothers you most is enough. We'll ask about the glass type and the measurements ourselves. If it's easier for you, call +420 739 374 074.

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